An azide function is often introduced in an organic molecule, in particular in a carbohydrate, during a multistep synthesis of compounds with amino groups. The introduction of the azide function can be accomplished by either azide substitution of an appropriate leaving group, such as tosylate, mesylate or chloride, or by addition of the azide-anion to an epoxide. For example, azidohydrins, potential precursors for 1,2-aminoalcohols can be prepared from epoxides by reaction with an alkali metal azide under alkaline or acidic conditions.
In most processes known in the art for the azide addition to an epoxide the process is carried out in a polar organic solvent at a temperature of approximately 100-110.degree. C., in combination with a buffering system such as ammoniumchloride, ammoniumsulphate, or tri-isopropylbenzenesulfonic acid/2,6-lutidine (Van Boeckel, et al., J. Carbohydr. Chem. 1985, 4, 293-321). Problems encountered with such processes is that side reactions may occur by the acidic or alkaline conditions leading to isomerisation, epimerisation, and rearrangement. A further serious drawback of the use of an ammonium salt is that ammoniumazide is formed, which is considered to be an explosive compound, and upon using ammoniumchloride also chloride can add to the epoxide instead of azide. The use of buffers consisting of a mixture of an organic base and an acid for pH control may give rise to the formation of hydrazoic acid. This is a highly toxic and explosive gas. In general, reactions with alkali metal azides cannot be performed in a stainless steel reactor, because there is a possibility that heavy metal azides, such as chromium- or nickel azide, are formed upon contact with the walls of the reactor. Such heavy metal azides are explosive in dry form. Furthermore the azide ion has the same corrosive properties as for instance the chloride or bromide ion. On the other hand, in a glass lined reactor serious corrosion of the glass lining at temperatures of 100-110.degree. C. also occurs. In particular this occurs under basic conditions when, for example, in using sodiumazide in water and dimethylformamide, the pH can rise to values over 12 due to the formation of sodiumhydroxide.